JP2004108657A - Method and device for treating high temperature exhaust gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively utilize sensible heat of exhaust gas and achieve decomposition of organic chlorine compound such as dioxin securely irrespective of use of simple facility. <P>SOLUTION: A ceramic filter 2 holding catalyst is provided in an exhaust gas flue at an outlet of an incinerator 1 or an outlet of a melting furnace to decompose organic chlorine compound in exhaust gas by dust removed from the exhaust gas and the catalyst in a temperature zone of 400°C or more. Scattered ash caught by the ceramic filter 2 is supplied into an external heat kiln type scattering ash treatment device 5 to heat it at temperature of 300°C or more in order to decompose dioxin by heat. Sensible heat of exhaust gas at an outlet of the ceramic filter 2 is utilized as its heat source. The exhaust gas at the outlet of the ceramic filter 2, inside exhaust gas from the inside of the scattering ash treatment device 5, and exhaust gas for external heat utilized as heat source are radiated into the atmosphere. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is a method for detoxifying high-temperature exhaust gas and fly ash containing organochlorine compounds such as dioxin, which is discharged from an incinerator or a melting furnace for municipal waste, sewage sludge, industrial waste, and the like, and It concerns the device.
[0002]
[Prior art]
Exhaust gas and fly ash emitted from incinerators or melting furnaces such as municipal waste and industrial waste contain organochlorine compounds such as dioxins that are harmful to the human body, and control those emissions. Technology is improving year by year.
[0003]
JP-A-2000-157840 discloses a method for removing an organochlorine compound contained in a high-temperature exhaust gas resulting from combustion of waste, for example, in a ceramic in which a catalyst is supported in a flue at an outlet of a waste incinerator or melting furnace. A filter is provided to collect dust in a temperature range higher than the resynthesis temperature of dioxins, and to decompose organic compounds and organic chlorine compounds. In addition, a boiler and a economizer are provided at the subsequent stage of the ceramic filter to recover residual heat of the exhaust gas, and the steam turbine generates electric power.
[0004]
As a method for treating dust ash, Japanese Patent Application Laid-Open No. 7-112172 discloses a kiln-type heating device that heat-treats dust ash in an exhaust gas treatment step of a waste incinerator to remove organic matter contained in the dust ash. Decomposes and removes chlorine compounds.
[0005]
Further, in Japanese Patent Application Laid-Open No. 9-57229, sensible heat of exhaust gas is recovered in advance by a boiler, and fly ash collected by a dust collector in an exhaust gas treatment process of an incinerator in the subsequent stream is granulated. The dioxins are decomposed by a heating device that uses an electric heater as an auxiliary heat source because the sensible heat collected by the boiler is used for the fly ash that has been granulated, and the sensible heat is insufficient.
[0006]
[Problems to be solved by the invention]
However, the exhaust gas treatment method disclosed in Japanese Patent Application Laid-Open No. 2000-157840 presupposes that all of the fly ash contacts the catalyst of the ceramic filter sufficiently. When the collected fly ash is cooled as it is, there is a risk that an organic chlorine compound such as dioxin is resynthesized.
[0007]
In addition, in the method of treating dust ash disclosed in Japanese Patent Application Laid-Open No. 7-112172, a separate heat source is required when heat-treating the dust ash, which raises operating costs and energy efficiency in the entire waste treatment facility. There is a low problem.
[0008]
In the fly ash treatment method disclosed in Japanese Patent Application Laid-Open No. 9-57229, the fly ash is granulated to increase the bulk density, increase the thermal conductivity, and increase the heating efficiency. In order to heat the granulated fly ash at a low temperature, sensible heat collected by a boiler is used to heat the low-temperature granulated fly ash. The thermal efficiency is low as a treatment process, and granulation equipment is essential, which is not desirable in terms of equipment cost.
[0009]
On the other hand, power generation is not always required in waste incineration facilities, and there is a need for a means of using sensible heat of exhaust gas other than in a steam boiler.
[0010]
Accordingly, a main object of the present invention is to provide a high-temperature exhaust gas treatment method and apparatus that can effectively utilize the sensible heat of exhaust gas and reliably achieve decomposition of an organic chlorine compound such as dioxin while using simple equipment. It is.
[0011]
[Means for Solving the Problems]
The present invention that has solved the above problems is as described below.
<Invention according to claim 1>
In the exhaust gas flue at the outlet of the incinerator or the melting furnace, a ceramic filter holding a catalyst is provided to remove the exhaust gas and to decompose the organochlorine compound in the exhaust gas by the catalyst,
Fly ash collected by the ceramic filter is supplied to an external heat kiln type fly ash treatment device and heated to thermally decompose dioxins, and the sensible heat of the ceramic filter outlet exhaust gas is used as a heat source thereof.
A method for treating high-temperature exhaust gas, wherein the exhaust gas at the outlet of the ceramic filter, the internal exhaust gas from the inside of the fly ash treatment device, and the exhaust gas for external heat used as a heat source are released to the atmosphere.
[0012]
(Effect)
In the present invention, dust is removed by a ceramic filter holding a catalyst. The high-temperature flue gas containing unburned matter, dioxins, and soot at the outlet of the incinerator or the melting furnace passes through a ceramic filter, and passes through gas components (N ₂ , O ₂ , CO ₂ , H ₂ O and Other small and trace gas components) exit from the gas outlet through the filter tube. At this time, the dust cannot pass through the filter tube, but adheres to the outside of the filter tube or falls downward. Further, unburned components (CO, HC, carbon, dioxins, etc.) are decomposed and burned by coming into contact with the catalyst when passing through the filter tube, and are converted into CO ₂ and H ₂ O. Therefore, substantially harmless exhaust gas is transferred to the path of emission to the atmosphere.
On the other hand, fly ash collected by the ceramic filter is supplied to an external heat kiln type fly ash treatment device and heated to thermally decompose dioxins. Therefore, the internal exhaust gas from the fly ash treatment device becomes substantially harmless exhaust gas, and can be released to the atmosphere. At that time, the sensible heat of the exhaust gas at the outlet of the ceramic filter is used as the heat source. Since the temperature of the exhaust gas hardly decreases in the ceramic filter, the sensible heat of the exhaust gas at the outlet of the ceramic filter can be sufficiently used, and the heat can be effectively used.
[0013]
Furthermore, the fly ash treatment device is of an external heat kiln type, so that the heat utilization efficiency is high, and the exhaust gas for external heat used as a heat source is substantially harmless, so that it is released to the atmosphere. be able to.
[0014]
Thus, a treatment process with high energy utilization efficiency, low equipment costs and low operating costs is obtained.
[0015]
<Invention according to claim 2>
A ceramic filter holding a catalyst is provided in an exhaust gas flue at an incinerator outlet or a melting furnace outlet, and when the outlet temperature of the ceramic filter is in a temperature range of 400 ° C. or more, dust removal of the exhaust gas and organic chlorine in the exhaust gas by the catalyst are performed. To break down the compound,
The fly ash collected by the ceramic filter is supplied to an external heat kiln type fly ash treatment device and heated at a heating temperature of 300 ° C. or more to thermally decompose dioxins, and as a heat source, sensible heat of exhaust gas from the ceramic filter outlet. Using
A method for treating high-temperature exhaust gas, wherein the exhaust gas at the outlet of the ceramic filter, the internal exhaust gas from the inside of the fly ash treatment device, and the exhaust gas for external heat used as a heat source are released to the atmosphere.
[0016]
<Invention according to claim 3>
The high-temperature high-temperature apparatus according to claim 1, further comprising a fly ash supply amount adjusting means for adjusting a supply amount of fly ash collected by the ceramic filter into the fly ash processing device, between the ceramic filter and the fly ash processing device. Exhaust gas treatment method.
[0017]
(Effect)
Smooth operation is possible by providing a fly ash supply amount adjusting means that adjusts the supply amount of collected fly ash into the fly ash treatment device according to the variation of the amount and properties of the incineration or melting target It becomes.
[0018]
<Invention according to claim 4>
The exhaust gas for the external heat used as a heat source and the internal exhaust gas from inside the fly ash treatment device are configured to merge with the emission path of the exhaust gas from the ceramic filter outlet to the atmosphere,
A pressure control valve that adjusts the pressure in the fly ash treatment device by adjusting the amount of the induced exhaust gas by the attraction blower and the attraction blower of the internal exhaust gas at a stage after the fly ash treatment device and to the junction,
A flow control valve that adjusts the flow rate of the external heat exhaust gas by adjusting the amount of the induced heat gas by the induction blower and the amount of the induction gas by the induction blower at the site after the fly ash treatment device and reaching the junction,
The method for treating high-temperature exhaust gas according to claim 1, wherein
[0019]
(Effect)
By providing a pressure control valve that adjusts the pressure inside the fly ash treatment device, the pressure inside the fly ash treatment device can be adjusted to an appropriate negative pressure state, and the thermal decomposition of dioxins can be qualified, It is possible to prevent undecomposed dioxins from transferring to the air release route. Further, by providing a flow control valve for controlling the flow rate of the exhaust gas for external heat, the heating temperature in the fly ash treatment device can be controlled.
[0020]
<Invention according to claim 5>
In the exhaust gas flue of the incinerator outlet or the melting furnace outlet, a ceramic filter that holds a catalyst and removes the exhaust gas and decomposes the organic chlorine compound in the exhaust gas by the catalyst,
An external heat kiln type fly ash treatment device for thermally decomposing dioxins in fly ash collected by the ceramic filter,
In order to use the sensible heat of the ceramic filter outlet exhaust gas as a heat source of the fly ash treatment device, an external heat gas introduction path that guides the ceramic filter exit exhaust gas to the fly ash treatment device,
Dissipation route of the ceramic filter outlet exhaust gas to the atmosphere,
An internal exhaust gas derivation route configured to join the internal exhaust gas from the inside of the fly ash treatment device to the radiation route,
A pressure control valve for adjusting the pressure in the fly ash treatment device by adjusting the amount of the attraction gas by the attraction blower of the internal exhaust gas and the attraction gas provided by the attraction blower, provided on the internal exhaust gas derivation path,
An external heat gas lead-out path configured to join the external heat gas from the fly ash treatment device to the radiation path,
A flow control valve that adjusts the flow rate of the exhaust gas for external heat by adjusting the amount of the attraction gas by the attraction blower of the external heat gas and the amount of the attraction gas provided by the induction blower,
A high-temperature exhaust gas treatment device comprising:
[0021]
(Effect)
The same functions and effects as those of the first and third aspects are obtained.
[0022]
<Invention according to claim 6>
The fly ash supply amount adjusting means for adjusting a supply amount of fly ash collected by the ceramic filter into the fly ash processing device is provided between the ceramic filter and the fly ash processing device. High-temperature exhaust gas treatment equipment.
[0023]
<Effects>
The same operation and effect as those of the third aspect are obtained.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.
FIG. 1 shows an overall configuration diagram of a high-temperature exhaust gas treatment apparatus according to one embodiment of the present invention. This embodiment is applied to a waste incinerator 1 or a melting furnace for incinerating waste such as municipal waste.
[0025]
The exhaust gas accompanying incineration in the incinerator 1 contains organic chlorine compounds such as dioxins. In the flue of the exhaust gas, a ceramic filter 2 holding (carrying) the catalyst C illustrated in FIGS. 2 and 3 is provided. In a temperature range of 400 ° C. or more, dust removal of the exhaust gas and organochlorine compounds in the exhaust gas by the catalyst are performed. Is decomposed.
[0026]
On the other hand, an external heat kiln type fly ash processing device 5 is additionally provided. The fly ash processing device 5 is, for example, a rotary kiln type, and an inner cylinder portion is rotated around an axis via rotary drive drums 5A, 5A. In addition, part of the exhaust gas passing from the outlet of the ceramic filter 2 to the atmosphere through the chimney 15 to the atmosphere 13 passes through the branched external heat gas introduction path 6 to the outer cylinder of the fly ash treatment device 5. The introduced sensible heat of the exhaust gas at the outlet of the ceramic filter 2 is used as a heating heat source of the fly ash treatment device 5.
[0027]
The external heat gas used as the heating heat source of the fly ash treatment device 5 is configured to merge with the radiation path 13 via the external heat gas outlet path 7.
[0028]
The external heat gas outlet path 7 is provided with an external heat gas induction blower 9 and an external heat exhaust gas passing through the outer cylinder portion of the fly ash treatment device 5 by adjusting the amount of the induction gas by the induction blower 9. A flow control valve 8 for adjustment is provided.
[0029]
In the ceramic filter 2, fly ash dust is collected and dropped at the lower part. The fly ash is continuously or intermittently cut out by the cut-out valves 3 and supplied into the fly ash processing device 5 by the fly ash supply amount adjusting means 4 including a screw conveyor or the like. The fly ash supply amount adjusting means 4 has a function of adjusting the fly ash supply amount into the fly ash processing device 5 in association with the rotation speed and the opening / closing timing of the cutout valves 3.
[0030]
On the other hand, the inside of the fly ash treatment device 5 communicates with an internal exhaust gas derivation path 12 configured to join the internal exhaust gas to the radiation path 13. A blower 11 and a pressure adjusting valve 10 that adjusts the pressure in the fly ash treatment device 5 by adjusting the amount of the induced gas by the induced blower 11 are provided.
[0031]
Thus, the fly ash collected by the ceramic filter 2 is supplied to the external heat kiln type fly ash processing device 5 by the cut-out valves 3 and the fly ash supply amount adjusting means 4, and the temperature is 300 ° C. or more, preferably 350 ° C. Heat treatment is performed at ~ 400 ° C, and the dioxins are thermally decomposed. The internal exhaust gas from the fly ash treatment device 5 becomes substantially harmless exhaust gas, and can be released to the atmosphere via the internal exhaust gas outlet path 12. Since the exhaust gas for external heat used as a heat source is substantially harmless, it can be radiated to the atmosphere through the external heat gas outlet path 7.
[0032]
Here, in the case where the pressure in the fly ash treatment device 5 is adjusted by operating the pressure adjusting valve 10 to adjust the amount of the attraction gas by the attraction blower 11, it is desirable to set the pressure to about -9.8 Pa to -294 Pa.
[0033]
In the ceramic filter 2, it is desirable to remove the exhaust gas and decompose the organic chlorine compound in the exhaust gas by the catalyst at a temperature range of 400 ° C. or higher, more preferably 500 to 700 ° C., at the outlet temperature of the ceramic filter. .
[0034]
On the other hand, if necessary, if the temperature of the exhaust gas is excessively high, a waste heat recovery facility 14 can be provided in front of the ceramic filter 2 to recover the waste heat.
[0035]
Further, other dust removal equipment such as a bag filter can be provided at a position downstream of the junction of the external heat gas outlet path 7 and the internal exhaust gas outlet path 12 with the dissipation path 13, but is usually unnecessary. Yes, it is possible to release the air as it is.
[0036]
In the ceramic filter 2, a partition wall 2B is provided at an upper portion in a shell formed of a cylindrical or prismatic container whose inner surface is covered with a heat-resistant material, and the partition wall 2B has a multiple exhaust gas inlet and an upper portion has an exhaust gas outlet. Is formed. A flow straightening plate for exhaust gas is provided as required. The arrangement of the filter tube 2A may be vertical or horizontal. As shown in FIG. 2, for example, the filter tube 2A has a cylindrical shape and is made of porous ceramic. A catalyst C is carried on the filter tube 2A. Also, a catalyst device (not shown) in which the catalyst C is carried on a honeycomb-shaped carrier can be provided on the downstream side of the ceramic filter 2 as necessary. Here, as the catalyst, a material having oxidizing activity is preferable, and examples thereof include transition metal oxides such as Cu, Co, Ni, and Fe, and noble metals or noble metal oxides such as Pt, Pd, and Ag. These may be used alone or in combination. Further, nitrogen oxides can be simultaneously decomposed and removed by using unburned CO and hydrocarbons in exhaust gas as a reducing agent. Therefore, metal ion-exchanged zeolites, metal-supported alumina, Ni—Ga spinel-based composite oxides, etc. When a nitrogen oxide reduction catalyst is used and a hydrocarbon fuel such as unburned gas is added, the reduction of nitrogen oxides is more effective.
[0037]
As an example of the dimensions of the filter tube 2A, the outer diameter can be 100 mm and the thickness can be 10 mm. Further, since the temperature of the high-temperature exhaust gas is usually 500 ° C. to 1000 ° C., the heat resistance of the ceramic may be about 1000 ° C. Further, the pore size may be about 3 μm in view of the particle size of the dust, and by setting the filtration speed to 0.5 to 2.0 m / min, the dust can be reduced to ³ to 6 g / Nm ³ to 10 to 50 mg / Nm ³ or less. Can be dropped. The high-temperature exhaust gas is passed from the outer surface to the inner surface of the filter tube 2A. The filter tube 2A needs to be backwashed with clean exhaust gas or air, because dust and soot may stay on the outer wall during use and cause clogging. Also, for this backwash operation, it is desirable that two or more filter assemblies be installed in parallel, with one running during the backwash.
[0038]
【The invention's effect】
As described above, according to the present invention, it is possible to effectively utilize sensible heat of exhaust gas and to surely achieve the decomposition of an organic chlorine compound such as dioxin while using simple equipment.
[Brief description of the drawings]
FIG. 1 is an overall flowchart of a high-temperature exhaust gas treatment process according to one embodiment of the present invention.
FIG. 2 is a perspective view of a filter tube.
FIG. 3 is a sectional view of a main part thereof.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Incinerator, 2 ... Ceramic filter, 3 ... Cut-out valves, 4 ... Fly ash supply amount adjusting means, 5 ... External heat kiln type fly ash processing apparatus, 6 ... External heat gas introduction path, 7 ... External heat Gas lead-out path, 8 ... Flow control valve, 9 ... Induction blower, 10 ... Pressure control valve, 11 ... Induction blower, 12 ... Internal exhaust gas lead-out path, 13 ... Dissipation path, 14 ... Waste heat recovery equipment, 15 ... Chimney.

Claims (6)

In the exhaust gas flue at the outlet of the incinerator or the melting furnace, a ceramic filter holding a catalyst is provided to remove the exhaust gas and to decompose the organochlorine compound in the exhaust gas by the catalyst,
Fly ash collected by the ceramic filter is supplied to an external heat kiln type fly ash treatment device and heated to thermally decompose dioxins, and the sensible heat of the ceramic filter outlet exhaust gas is used as a heat source thereof.
A method for treating high-temperature exhaust gas, wherein the exhaust gas at the outlet of the ceramic filter, the internal exhaust gas from the inside of the fly ash treatment device, and the exhaust gas for external heat used as a heat source are released to the atmosphere. A ceramic filter holding a catalyst is provided in an exhaust gas flue at an incinerator outlet or a melting furnace outlet, and when the outlet temperature of the ceramic filter is in a temperature range of 400 ° C. or more, dust removal of the exhaust gas and organic chlorine in the exhaust gas by the catalyst are performed. To break down the compound,
The fly ash collected by the ceramic filter is supplied to an external heat kiln type fly ash treatment device and heated at a heating temperature of 300 ° C. or more to thermally decompose dioxins, and as a heat source, sensible heat of exhaust gas from the ceramic filter outlet. Using
A method for treating high-temperature exhaust gas, wherein the exhaust gas at the outlet of the ceramic filter, the internal exhaust gas from the inside of the fly ash treatment device, and the exhaust gas for external heat used as a heat source are released to the atmosphere. The high-temperature high-temperature apparatus according to claim 1, further comprising a fly ash supply amount adjusting means for adjusting a supply amount of fly ash collected by the ceramic filter into the fly ash processing device, between the ceramic filter and the fly ash processing device. Exhaust gas treatment method. The exhaust gas for the external heat used as a heat source and the internal exhaust gas from inside the fly ash treatment device are configured to merge with the emission path of the exhaust gas from the ceramic filter outlet to the atmosphere,
A pressure control valve that adjusts the pressure in the fly ash treatment device by adjusting the amount of the induced exhaust gas by the attraction blower and the attraction blower of the internal exhaust gas at a stage after the fly ash treatment device and to the junction,
A flow control valve that adjusts the flow rate of the external heat exhaust gas by adjusting the amount of the induced heat gas by the induction blower and the amount of the induction gas by the induction blower at the site after the fly ash treatment device and reaching the junction,
The method for treating high-temperature exhaust gas according to claim 1, wherein In the exhaust gas flue of the incinerator outlet or the melting furnace outlet, a ceramic filter that holds a catalyst and removes the exhaust gas and decomposes the organic chlorine compound in the exhaust gas by the catalyst,
An external heat kiln type fly ash treatment device for thermally decomposing dioxins in fly ash collected by the ceramic filter,
In order to use the sensible heat of the ceramic filter outlet exhaust gas as a heat source of the fly ash treatment device, an external heat gas introduction path that guides the ceramic filter exit exhaust gas to the fly ash treatment device,
Dissipation route of the ceramic filter outlet exhaust gas to the atmosphere,
An internal exhaust gas derivation route configured to join the internal exhaust gas from the inside of the fly ash treatment device to the radiation route,
A pressure control valve for adjusting the pressure in the fly ash treatment device by adjusting the amount of the attraction gas by the attraction blower of the internal exhaust gas and the attraction gas provided by the attraction blower, provided on the internal exhaust gas derivation path,
An external heat gas lead-out path configured to join the external heat gas from the fly ash treatment device to the radiation path,
A flow control valve that adjusts the flow rate of the exhaust gas for external heat by adjusting the amount of the attraction gas by the attraction blower of the external heat gas and the amount of the attraction gas provided by the induction blower,
A high-temperature exhaust gas treatment device comprising: The fly ash supply amount adjusting means for adjusting a supply amount of fly ash collected by the ceramic filter into the fly ash processing device is provided between the ceramic filter and the fly ash processing device. High-temperature exhaust gas treatment equipment.

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